In the field of mobile radio such as in, for example, wirefree baseband systems for intelligent telephones (smart phones) and personal digital assistants (PDA), designs with systems on one chip (SoC; SoC=System-on-Chip) are used. These designs are complex heterogeneous systems which are composed of a hardware platform such as, for example, processors, buses, memories and peripherals, and software modules such as, for example, device drivers, firm ware, operating systems and applications. The SoC designs have, in particular, a plurality of processor cores which access different memories integrated in the chip, or external memories.
Wirefree baseband systems are usually divided into a modem subsystem and an application subsystem. In the modem subsystem, software modules such as firm ware, protocol stacks, device drivers and real-time operating systems (RTOS; RTOS=Real Time Operating System) are implemented, these being made available particularly by device manufacturers (OEM; OEM=Original Equipment Manufacturer) and chip manufacturers. In contrast, in the application subsystem, in addition to device drivers and operating systems (OS), software modules such as audio, video, game, e-mail, Internet, office and e-commerce applications are implemented, said applications being made available by end users and service providers. The software modules upgrade the wirefree baseband systems by enlarging, for example, their range of application.
The requirements made of the hardware platform increase as a result of the number and complexity of the software modules which are implemented in the different processor cores and processors and are made available by numerous different manufacturers. Owing to the different priorities and security requirements of the software modules it is therefore particularly important to keep the baseband system stable and to protect, in particular, the software of the equipment manufacturer (OEM) against mutilation and modifications by software applications of the end user.
If a plurality of processors access one memory there is therefore a problem in maintaining data integrity and data security of each software application which is assigned to a processor.
FIG. 2 shows a known design of a system on a chip (SoC) which solves this problem. The system 1 has two processors 2 and 3 which are connected via interfaces 4 and 5 to separate external memories 6 and 7. Each processor 2, 3 operates on its own memory 6, 7. A further, system-internal memory 8 is arranged between the processors 2 and 3. Data integrity and data security are ensured by virtue of the fact that the processors 2 and 3 have different execution environments as a result of the use of the external memories 6 and 7. The communication between the processors 2 and 3 is ensured via the system-internal memory 8.
A disadvantage of this design is that a plurality of interfaces with external memories having an assigned logic and assigned connection areas are necessary, which increases the complexity of the design.
A further disadvantage is that an additional system-internal memory is necessary in order to permit communication between the processors, which also increases the complexity of the design.